Recently, with the advancement of craft techniques and the improvement of living standards, people who intend to buy a new product consider not only the price and durability of the product, but also whether the product is convenient and safe to use. Such a change in market trends has driven manufacturers and designers in all fields to develop new and better products on a regular basis so as to meet consumers' needs. Take the assisted-opening folding knife commonly used in outdoor recreational activities for example. The conventional assisted-opening folding knife, though compact in size and easy to carry around, leaves much to be desired in terms of the blade opening and closing structure. More particularly, if the blade is held too tightly in the handle of the knife, the user will have problem opening the blade smoothly. However, if too much emphasis is placed on the smoothness of movement of the blade, the knife may injure the user by accident while being carried. To overcome the aforesaid problems regarding the folding and unfolding control of the conventional assisted-opening folding knife, many improvements have been made to the assisted-opening folding knife structure.
For instance, please refer to FIG. 1 for the assisted-opening folding knife structure, the assisted-opening folding knife 1 includes a blade 11, a handle 13, and a pushing element 15. The blade 11 has a first recess 111 and a second recess 113, both adjacent to one end of the blade 11. The handle 13 includes a first plate 131, a second plate 132, a third plate 133, and a fourth plate 134. A pivot 135 is pivotally provided adjacent to one end of the plates 131, 132, 133, 134 so that a portion of the blade 11 that is adjacent to the aforesaid end thereof is pivotally connected between the second plate 132 and the third plate 133 by the pivot 135. In addition, a first spring 135a is mounted around the pivot 135 so as to exert a resilient force on the blade 11 for spinning the blade 11 out of the handle 13. The first plate 131 is formed with a push slot 131a adjacent to the pivot 135. The second plate 132 is formed with a first positioning slot 132a adjacent to the pivot 135, and the third plate 133 is formed with a second positioning slot 133a corresponding in position to the first positioning slot 132a. Also, the third plate 133 has a side facing the second plate 132 and fixedly provided with a fixing portion 133b. The fourth plate 134 is concavely provided with a third recess 134a, in which a second spring 134b is disposed. The pushing element 15 is provided with a first post 151 and a second post 152. The pushing element 15 is positioned between the first plate 131 and the second plate 132 and corresponds in position to the push slot 131a. Hence, the first post 151 is exposed through the push slot 131a while the second post 152 passes through the first positioning slot 132a and the second positioning slot 133a. As a result, one end of the second post 152 is positioned in the third positioning slot 134a and connected with the second spring 134b. The second spring 1346 biases the pushing element 15 toward the pivot 135. When the blade 11 is completely received between the second plate 132 and the third plate 133, the second post 152 presses against the second recess 113 of the blade 11 and thereby prevents the blade 11 from being rotated out of the handle 13. Meanwhile, the edge of the blade 11 is pressed against the fixing portion 133b. Thus, the blade 11 is securely positioned in the handle 13. When it is desired to open the blade 11, the pushing element 15 is pushed away from the pivot 135 to release the blade 11 from the pressing force of the second post 152, thereby causing the blade 11 to spring out of the handle 13. Once the blade 11 is driven out completely, the resilient force of the second spring 134b pushes the pushing element 15 toward the pivot 135 such that the second post 152 is pressed against the first recess 111 of the blade 11 to ensure that the blade 11, when used in cutting in this position, remains firmly positioned in the handle 13. The user only has to push the pushing element 15 away from the pivot 135 again, and the blade 11 is freed from the pressing force of the second post 152.
Although the conventional assisted-opening folding knife 1 can spin the blade 11 smoothly out of the handle 13 and guarantees the safety of carrying the knife 1 around, the knife 1 still has the following drawbacks:
(1) Complicated handle structure: As the handle 13 of the assisted-opening folding knife 1 is composed of at least four plates, the production cost of the assisted-opening folding knife 1 is undoubtedly higher than those of other conventional assisted-opening folding knives, which in turn affects the selling price and market competitiveness of the assisted-opening folding knife 1.
(2) Inconvenient knife folding mechanism: To fold the blade 11 into the handle 13, it is required to push the pushing element 15 away from the pivot 135 so that the blade 11 is released from the pressing force of the pushing element 15. Therefore, in order to put the blade 11 in between the second plate 132 and the third plate 133, the user must push the pushing element 15 with the knife holding hand and then rotate the blade 11 with the other hand. In other words, the knife folding process cannot be completed single-handedly. As assisted-opening folding knives are intended to be convenient, a simpler knife folding mechanism will definitely increase consumer satisfaction.
(3) Knife safety issues: Although the second post 152 of the pushing element 15 presses against the end of the blade 11 that is adjacent to the pivot 135 when the blade 11 is received in the handle 13, the blade 11 will be released and driven out of the handle 13 by the torque of the first spring 135a as soon as the pushing element 15 is pushed. Therefore, if the user is not careful enough, the assisted-opening folding knife 1 is very likely to cut the user during use.
In fact, there are a good number of products on the market that are similar to the assisted-opening folding knife 1 and designed to facilitate the opening and closing of the blade without compromising safety. For example, another prior used structure and method for closing the blade of a folding knife are shown in FIG. 2, the folding knife can be easily provided with an additional spring and thus turned into an assisted-opening folding knife. Because of that, the folding knife is also referred to hereinafter has an assisted-opening folding knife. As shown in FIG. 2, the assisted-opening folding knife 2 includes a blade 21 and a handle 22. The blade 21 has one end concavely provided with an engaging groove 211, and the handle 22 is provided with a pivot 221 and a recess 222. A portion of the blade 21 that is adjacent to the aforesaid end thereof is pivotally connected in the handle 22 by the pivot 221. The recess 222 is provided therein with a pushing element 222a and a spring 222b. The pushing element 222a has a first end pivotally connected to the handle 22. The spring 222b applies a pushing force to the pushing element 222a to bias the pushing element 222a toward the pivot 221 such that a second end of the pushing element 222a is engaged with the engaging groove 211. Therefore, if the blade 21 attempts to rotate toward the handle 22, the blade 21 will be stopped by the second end of the pushing element 222a. In order to release the blade 21 and put it into the handle 22, the user must push the pushing element 222a and thereby drive the second end of the pushing element 222a away from the pivot 221. Although the assisted-opening folding knife 2 is improved in structural complexity over the assisted-opening folding knife 1 shown in FIG. 1, the blade 21 of the assisted-opening folding knife 2 is closed in the same way as the blade 11 of the assisted-opening folding knife 1. In short, the structures of both conventional assisted-opening folding knives described above can only ensure the secureness and safety of the knives in the folded state but do not provide improvement in smoothness of use. The same is true of all commercially available assisted-opening folding knives.
Therefore, the issue to be addressed by the present invention is to design an assisted-opening folding knife which not only can pop out the blade smoothly but also can minimize the effort required to put the blade into the handle, thus allowing the user to close the blade in a more intuitive and natural manner.